terraformingfandomcom-20200214-history
Dead Planet
The concept appears throughout sci-fi literature and sci-fi movies, but it was probably coined for the firs time in the Soviet novel Silent Empire. Some post-apocalyptic movies describe the Earth as being so, the best and most known example is the Earth in Matrix. Basics A dead planet is a planet which was once populated by living organisms. After a catastrophic event, mostly caused by humans or another intelligent form of life, life went extinct, usually by blocking plants ability to do photosynthesis. Still, average temperature remains within acceptable boundaries, water is drinkable and the air remains breathable. Humans can survive there if they produce food in enclosed systems. Examples The following examples are from sci-fi literature and post-apocalyptic movies: In Silent Empire, the Futurers (an advanced and ultra-evolutionist race) consider all other human races as suboids and try to exterminate or enslave them. They try to transform all planets into a copy of their home planet (see YZ Planet for details). Whenever they encounter a civilization that refuses to surrender, they send a virus that blocks chlorophyll molecules. Plants die, then animals starve. Humans fight with each other as cannibalism becomes the only way to survive. In Matrix, humans burn the sky, creating a thick layer of clouds that block the light from the Sun from reaching Earth. Machines, dependent on solar power, have to adapt, while all life on Earth, except humans and artificially grown bacteria, is extinct. In The Road, on Earth, a massive flame destroys all plant life and all humans that were not indoors. 18 years later, the last humans survive by cannibalism and by searching the little food left behind from before. The Doctor Who series presents a planet at the end of time. There is no star to light that planet, which has a thermal shield, keeping surface temperatures suitable for human life. Probably, it had an Artificial sun which recently went extinct. There are many other examples, both in sci-fi literature and in movies. All of them come with a similar principle, the destruction of plant life, while temperature and atmosphere are not affected. Possible causes A terraformed planet can end-up as a Failed Earth if something goes wrong. For example, a bad management of Greenhouse Gases or of Anti Greenhouse Technology can transform a planet into a Fireball Earth or a Snowball Earth. Also, Atmosphere around small bodies is not stable. But, in these scenarios, the planet becomes no longer habitable because of natural disasters and lacks of funds for Maintaining a terrafomed world. In case of a dead planet, there are no natural causes that can make this happen. The causes must be artificial. If we think that future acts of terrorism and Future wars are possible, we can speculate that the only cause of dead planets will be of human activity, almost always badly intentioned. Blocking the light In Matrix, humans created an artificial layer of clouds, blocking sunlight and forcing life on Earth to be extinct. However, as shown in Plants on new worlds, Earth-like plants can survive with a luminosity of 1/1000 of what is on Earth's orbit. Earth-like plants can survive as far as the orbit of Neptune. So, blocking light form the Sun will require very thick clouds. Not the same can be said about an Outer Planet, for example a terraformed Titan or Triton. In this case, it will be easy to diminish the amount of light. Even more catastrophic results can be obtained in case of M - type stars, also known as red dwarfs. These tiny stars produce most of their light in infrared. In visible spectra, most of their light is red, with little blue. Plants need both red and blue light to survive. Already, Earth-like plants on a planet orbiting a red dwarf, should have a harsh life, trying to use the little blue light they receive. It is possible that on many such planets settlers will use artificial blue light from an orbital station. If you destroy the station, you destroy the plants and you make such a planet become dead, without a significant impact on temperature. Natural events The only thing that can destroy life on a planetary scale is a gamma ray burst. Such bursts are created by Neutron stars or when a star goes supernova. Still, they will only hit one hemisphere. And even so, they don't pierce too deep into the oceans. So, they will destroy all life. Orbit shift What would happen to the Earth if one day it will be ejected from orbit, becoming a Runaway Planet? It will freeze. First, the atmosphere will freeze, then the surface of the oceans. Life will still exist for a long time under the ice, in the oceans, mainly in thermal vents. However, thermal vents shift their position on long periods of time, as plate tectonics change. It is possible that plankton will not make it to the next thermal vents. Life can survive a long time frozen. Seeds and bacteria might resist for thousands of years, but we don't know what will happen in millions of years. Let's suppose that after a billion years Earth is captured by the gravity of another star and enters orbit in the habitable zone. What will happen? The atmosphere will form again from frozen gasses deposited on the surface. The oceans will form again too. Earth will become a habitable planet again, but without life to benefit from this. It will be a dead planet. Biologic weapons In Silent Empire, the Futurers used a virus to block chlorophyll. This way, all plants died because they were unable to make photosynthesis. We have biological weapons, but nobody was able to create such a virus yet. Still, the scenario seems plausible for a more advanced civilization. Mass destruction weapons Is it possible to destroy all life with the use of powerful weapons? Many people focused on a possible nuclear holocaust, like what is supposed could happen during world war 3. But will it be like this? Many scientists argue that life will not end. Bacteria was found to survive even inside nuclear reactors. And even if we scourge the Earth with massive explosions, deep inside the oceans, life will be unaffected. The Fire Flood is a method of terraforming, in which, a planet is heated to a runaway global warming. Oceans boil. Such a method is to be used when a planet is devastated by a deadly disease. Hot heat can sterilize, killing all viruses and bacteria. In the hot environment of a fire flood, many chemical reactions happen. The method is also suitable when we want to remove some toxins, which can be neutralized this way. However, oxygen in the atmosphere will become far more reactive and will interact with rocks. After we cool a planet from a fire flood, we might no longer find a breathable atmosphere. Still, it is possible to burn all plants and animals on the surface, also killing all algae, keeping the atmosphere breathable. Even if life will remain deep inside the oceans, those organisms don't need light to grow and are not suitable for human food. Halted terraforming Another scenario that can produce a dead planet is a halted terraforming process. It is possible to terraform a planet without the use of life. We can produce oxygen from water or from carbon dioxide via electrolysis. Imagine this scenario: A galactic company starts the terraforming of a planet. Everything goes well, up to the moment when they must do Insertion Of Earth-like Life. At that point, their funds are cut off and they have to stop. The resulted planet will be habitable, but will be dead. Timeline The evolution of a dead planet is interesting and can be divided into a few distinct steps. Cannibalism era If plants cannot use light, they will soon run out of resources. Animals will continue to feed, destroying plants. The remaining plants will run out of resources soon and will die. Plants should remain on the planet for only a few months. As plants start to die, herbivores will be affected. Carnivores will feed on the more weaken herbivores, causing their extinction. In the end, carnivores will start to feed one with each other, up to the point where they will also face extinction. The last to die will be bacteria, who will feed on everything left behind. Humans will feel the disaster as well. In a less advanced civilization, this will come with massive famines that will dramatically reduced population gradually. There will be wars for the remaining grain deposits. Then, cannibals will be the last to survive. In the end, they will face extinction too, if they cannot produce food somehow. An average human needs 2870 calories. A human body has an average of 110000 cal. This means a cannibal will need a human body every 38 days (so, one every Earth month). In this scenario, world population will be reduced in an year from 5 billions to 1.22 millions, in two years to only 298 people and in 3 years to zero. Oxygen decay era What would happen on a long timescale on a dead planet? First of all, oxygen concentration is slowly decaying. Oxidation reactions occur in nature. Occasional fires will be the first to be sensed. On a longer timescale, oxidation of various rocks becomes relevant. Also, as time passes, more oxygen will be dissolved in ocean water. In the same time, small amounts of carbon dioxide are released into the atmosphere, both from oceans and lakes and from volcanoes. The atmosphere will be breathable for centuries, if not for millennia. Humans will first endangered by the increase of concentration of carbon dioxide and other dangerous gasses, long before oxygen falls below critical concentrations. What will happen before this, is a change in atmosphere ionization, which can affect the health of those living on a dead planet. In encased systems (like a cave or an underground chamber), free oxygen atoms and various oxidizing radicals will form, with dangerous effects on the health of those living there. An advanced civilization can grow plants in artificial conditions, using a source of light. For a very long term, they can grow plants outside and they can live outside, until the atmosphere is no longer breathable. Back to life From all celestial bodies, a dead planet is the most easy to terraform (or re-terraform). All settlers will need is to make somehow photosynthesis possible. Then, plants can be inserted and they will transform their world back into a paradise. Category:Terraformed models